It is the central tenant of Core B and this program project that the most appropriate method to study MH is in murine models that expresses frequently seen human MH mutations. Mouse models can provide sufficient tissues for molecular, biochemical, cellular, and physiological analyses by a multidiscipiinary team whose collective goal is to understand the etiology of these myopathies. The use of mice also permits these analyses to be performed in diverse genetic backgrounds. Core B will perform the repetitive tasks that are necessary to support all four Projects. This core will provide an important and integrated facility to receive gene-targeting constructs from Project 1 and Project 3. They will transfect these constructs into ES cells and after the projects identify homologously targeted clones, amplify these clones for blastocyst injection and inject these targeted ES cells into blastocysts to produce chimeras. After confirmation of germline transmission by Projects 1 and 3, Core B will produce MH "knock-in" mice to be studied by all four Projects. Core B will take cDNA constructs from Projects 1, 3 and 4 and package them into HSV1 (RyRs) or Lentivirus (DHPRs) virions to be used for expression of mutated proteins and intracellular reporters in myotube cultures and distribute them as needed to all 4 projects. Core B will make myoblast cell lines from all heterozygous and homozygous MH "knock-in" mice and maintain dyspedic, dysgenic and dyspedic/dysgenic cell lines to be used by all 4 projects. Core B will receive human MHS muscle samples from Core C and maintain myoblast cell lines from these samples to be used by projects 1 and 4. In addition to maintaining MH "knock-in" animal lines Core B will take responsibility for interbreeding these animals with C57BL6 and BalbC mice to produce MH animals with different genetic backgrounds The uniform and consistent supply of exactly the same study models to all four Projects by this Core will allow a truly integrated approach to the study of Malignant Hyperthermia.